One of the first things I did when I visited London a few years ago was to go on a Sherlock Holmes walking tour. I’m not the only avid reader compelled to seek out the real-life settings found in books. This desire is what has brought about Placing Literature, an interactive site dedicated to plotting scenes from books onto real-world maps. It’s like a heady mixture of a database, Google Maps, and the efforts of a bunch of literature geeks.

In a small office near Central Square in Cambridge, Massachusetts, just across from Starbucks, is a small startup with a big idea for balancing biodiversity with business. SilviaTerra has developed better ways to identify and quantify the trees in forests, using smartphones and satellite imagery. The company’s goal is to help landowners, conservation groups, and timber companies manage their inventory and preserve valuable natural habitats.

With airplanes flying over regularly, and sweat dripping from his brow, the president unveiled the most ambitious climate change plan in American history today in a speech at Georgetown University. The biggest unexpected news: among his proposals, detailed here, the president set a critical emissions measure for approval of the Keystone XL pipeline.

Obama’s rhetoric was typically powerful. “As a president, as a father, and as an American, I am here to say: We need to act.”

“At the center of a star, the core is so dense that nuclear interactions take place and as a result, light comes out. And basically, the light that comes out of a star is brighter and reactions are faster the larger the star is,” Bettencourt said. “That’s a little bit like what cities do, too. It’s mathematically different, but the larger the population is, the faster the rates of social interaction.”

“Stars are nuclear reactors and cities are a different kind of reactor,” he added. “They are social reactors.”

Bettencourt, in a paper published today in the journal Science, finally offers up an answer that borrows a bit from physics, economics, sociology, biology and a handful of other disparate reaches of science. We can never get the analogy quite right, he says, because cities are a thing that is found nowhere else in nature.

“We tend to look at things by the way they look, by form,” he says. And this is why most of our existing metaphors fail. “All the successful theories of science are not about form at all – they’re about function. They’re about how things develop, how things change. They’re about process.”

While this model does not explain regional aspects of cities or the disparities within an urban environment, as Bettencourt notes—it is ultimately about the city as a whole—it is a powerful means of understanding how cities, and the people within them, operate. Ultimately, cities are an instantiation of the optimal configuration for social interactions, and this is a great quantitative exploration of how they work.

Cities, it seemed, had been abandoned by science. When all the other disciplines and systems were being quantified and theorized, cities were largely ignored. Cities didn’t have a grand unified theory or a theory of everything. Hell, for the most part they didn’t even have a theory of something. People pieced together bits and bobs here and there, but there was no wide-scale model to describe what is the greatest collection of systems ever devised by humanity.

That may be changing, though. Luis Bettencourt, whose work I’ve written about before, published a new paper today in which he claims to have developed a unified theory of the city. Like his previous research, it focuses on scaling in cities—what patterns and processes share mathematical similarities across cities of all sizes. Bettencourt takes a functional approach, studying what he believes are cities’ reasons for being, social interaction.

Bettencourt believes there are four sparks that cause cities to form—the mixing of populations, the incremental growth of networks, the bounds of human effort, and the relationship between socioeconomic output and personal interaction. According to these assumptions, cities are founded and grow primarily so that people can interact frequently and on a personal level. As demand for face time swells, cities expand, incrementally adding to the existing network. Eventually, those networks reach a limit, bounded by the amount of effort we are willing to expend to expand and maintain them. The greater the benefit of living in a city, the more effort we’re willing to expend to sustain it. Bettencourt’s final assumption may be his most astute—that cities aren’t just agglomerations of people, but also concentrations of social interactions.

The formulas Bettencourt derived could prove powerful. His most muscular equation, that which models city growth, identifies cities that punch above and below their weights. Others show how substandard transportation can hold a city back, or how transportation networks tend to grow incrementally (perhaps that’s why automobile sprawl seems so intractable). But his formulas also highlight some perils, like how energy loss in transportation increases superlinearly—the more you move, the more energy it takes to move something. In sum, they appear to build a solid theoretical framework by which further questions can be asked and hopefully answered.

Those of us who have been arguing for a science of cities¹ will find promise in Bettencourt’s work. It’s a strong first step, though I hesitate to declare victory and go home. It’s a theory based in data, but it’s still just a theory. Until it and other models are devised and tested experimentally, we won’t have a true, robust science of cities.

So what took us so long to get to this point? Why is it only now that we’re developing a true theory of the city? I have a couple theories. First, when many disciplines were delving into the world of theory—the 1940s through the 1970s—cities were thought to be relics of the past. Our newfound mobility had enabled us to leave the polluted, crime-ridden warrens behind, so why would we want to spend our time thinking about soon-to-be-obsolete cities? Only recently have we reevaluated urban areas, holding them in higher esteem than just a few decades ago. The other possibility is that cities are intensely complex, and that complexity is further complicated by the fact that we created it. Any time humanity is involved, the level of anxiety and detail ratchets up immensely. With cities and other human-based systems, it can be tricky to separate ourselves from the equations.

The current science of cities seems at about the state ecology was during the late 1960s and early 1970s. Then, overarching theories were new to the field, as they are now with cities. But because we’re already collecting so much data on cities—much more than is collected on the natural environment, I’d warrant—I expect urban science to evolve more rapidly. The gap will close, and perhaps someday the science of cities² will teach ecology a lesson or two.

There has got to be a better term for this. Metropology? Sounds weird. Urbanology? Even weirder. Urbanistry? Whatever. We’ve got to find something better than “science of cities”. It just sounds lame, alliteration be damned. ↩

Everett believes the conditions at higher altitudes may encourage the production of ejective phonemes [a basic unit of sound—a type of phoneme—which when combined with other phonemes create words]. These utterances require that the vocal cords are closed and raised. Everett holds that this is easier to accomplish at higher altitudes where atmospheric pressure is lower, which means that air pressure in the mouth and lungs is lower so it may be easier to force the vocal cords closed. Everett also proposes that the higher incidence of ejective phonemes at higher altitudes may represent a biological adaptation.

There are many ways to demolish a building, and some of them are spectacular: blowing it up from the inside so it collapses on itself, or smashing it to bits with a two-ton wrecking ball.

But here in Tokyo, a cheek-by-jowl city with many outdated high-rises and tough recycling and environmental restrictions, Japanese companies are perfecting what might be called stealth demolition. Some tall buildings are dismantled from the top down, the work hidden by a moving scaffold, others from the bottom up, the entire structure being slowly jacked down.

Pregnancy has allowed me for the first time to understand how hard it is to tell good information from bad. As a science journalist, I make my living by being able to decipher the two, but all these warnings bewilder me. As a result, I feel like I can see a bit more clearly how misinformation can become epidemic, leading to collective panic and seriously bad policy making.

It’s named after the first three digits of most Chicago zip codes and is supposed to connote a connection to the trail’s railroad past. The first I get, even if it’s a bit hokey. But I’m having trouble with the last. Most rail corridors I know are named, not numbered. Plus, “The 606” makes me think of freeway in Southern California, not a rail trail in Chicago.

David Yanofsky created a clever series of maps illustrating the average “destination” of international flights originating from a particular country. The average destination for U.S., for example, is somewhere in northeastern Quebec.

What’s more important in these maps than the destination—and what goes unsaid in Yanofsky’s article—are the length and direction of the vectors. I suspect they’re telling us something about real-world international relations. Not the diplomatic sort, but who everyday people are interacting with.

Since the 2008 economic crash, security agencies have increasingly spied on political activists, especially environmental groups, on behalf of corporate interests. This activity is linked to the last decade of US defence planning, which has been increasingly concerned by the risk of civil unrest at home triggered by catastrophic events linked to climate change, energy shocks or economic crisis – or all three.

The current world population of 7.2 billion is projected to increase by 1 million over the next 12 years and reach 9.6 billion by 2050, according to a United Nations report launched today, which points out that growth will be mainly in developing countries, with more than half in Africa.

Here’s the scam. A Chinese company manufactures hydrofluorocarbons, the refrigerant gases responsible for the ozone hole and climate change. The gases can efficiently be turned into cash, either by using them in products like refrigerators or air conditioners or, more lucratively, by destroying them. In the early part of the last decade, Chinese manufacturers of HFCs made more and more of them—more than necessary for use even in the rapidly growing Communist country—because the international market for buying and selling the right to pollute with greenhouse gases awarded credits for their destruction. The gas could be made more cheaply—and then destroyed—than the carbon credits that resulted from their destruction were worth. All told, Chinese manufacturers netted billions of dollars in profits from an international effort meant to pay for developing countries to reduce pollution via projects such as preventing forests from being cut down or building more expensive renewable energy projects.

So when the Chinese agree to phase out HFCs, as their President Xi Jinping apparently did with U.S. President Barack Obama, they should be applauded—and shamed. Such cons are the most insidious reason why the world is not on track to restrain global warming to just 2 degrees Celsius, and could see average temperatures more than 5 degrees C higher if more efforts are not made.